[hmscott]

Heads up, I posted some responses from Xudoo on opamp's used on the TA-20 to the Opamps thread:
https://www.head-fi.org/threads/the-opamp-thread.432749/post-16699436

 

[hmscott]

I also had the a90 then I sold it and I got the TA-20 I'm very satisfied, I installed some G.E. 5814 with five green stars and the TA-20 sounds great.
Get to know the G.E. 5814a?

I had heard those were a good choice, the GE 5814(a) series, especially the 3 Mica and 5 Star - IDK if Green vs White 5 Star makes a difference in build, it might be Green was added when printing color came into vogue.

The Brimar Yellow T 6060 tubes for instance came out in the 1950's, but weren't printed Yellow, they had a temperature safe plastic applique for the Big Yellow T

When I started out with the TA-20 I bought a pair of Phillips JAN 5814A:

And they sounded good, but nothing like what I've heard since moving to 12AT7/ECC81/E180CC/E80CC tubes. I've found I prefer the 12AT7 specification tubes over the 12AU7 and equivalent, like the 5814A. But, I haven't heard the Green 5 Star GE 5814a's yet

I've read the GE 5814a Green 5 Star tubes have the best sound of the series, but there are a lot of Military spec tubes also available - 5 White Star, and JG-5814A, all with 3 Mica and Square D Getters. Have you tried any of those? should I try those when I find them?

I would think the White labeling would be older tubes - usually built to higher Mil spec, than the commercial Green 5 Star's, but sound tells through the specs, have you tried White 5 Star's of the same or better specification to the 5 Green Stars?

Color tube labels came out the 70's/80's well after the Golden age of tubes - so far the 50's/60's tube have been the sweet spot. The 50's sound as good but the 60's built can have lower noise measurements.

Right now, these two are my favorites, I received the lower noise measuring '68 build tubes yesterday:

RARE Matched Quad Mullard NOS/NIB M8162/ECC81/12AT7 Dual getter support tubes (1968)
https://www.ebay.com/itm/174841732527

RARE Matched Pair Mullard NOS/NIB M8162/ECC81/12AT7 Dual getter support tubes (1968)
https://www.ebay.com/itm/175054641567

RARE Mullard NOS/NIB M8162/ECC81/12AT7 Dual getter support Copper plates tube (1968)
https://www.ebay.com/itm/174346933341

These are the first set I received in September, and still enjoy:

RARE Matched Quad NOS/NIB GEC/Mullard B309/M8162/CV4024/12AT7WA/ECC81 tubes 1958
https://www.ebay.com/itm/174325851178

RARE Matched Pair NOS/NIB Mullard GEC/B309/M8162/CV4024/12AT7WA/ECC81 tubes 1958
https://www.ebay.com/itm/174910341182

RARE GEC/Mullard NOS/NIB B309/M8162/CV4024/12AT7WA/ECC81 tube - England 1958
https://www.ebay.com/itm/184391947782

If you find any Green 5 Star GE 5814a Quad/Pair, please let us know

Update: @cirodts It looks like desireme1979 an ebay seller I trust has a bunch of GE 3 Mica 5814a variants in stock with 100%+/100%+ measurements - plus/minus - but no Green 5 Star GE's...should I give any of these a try?
https://www.ebay.com/sch/m.html?_ssn=desireme1979&_osacat=0&_armrs=1&_odkw=&_nkw=GE+3+mica&_sacat=0

 

[hmscott]

Moving discussion from here:
https://www.head-fi.org/threads/the-opamp-thread.432749/post-16699436

Thank you so much for the info. I did try to find info about this in the Xduoo thread as well, but i guess i didn't look well enough
Anyways, i do use the balanced inputs from my ADI-2 dac. So i guess there's no need to change anything. And i do have a pair of mullards on the way here, as well as some other tubes, can't even remember which ones atm. Sorry for hijacking this thread, i'll continue about this in the xduoo thread

-Pete

Yeah, not much out there on swapping TA-20 opamps, likely due to the small clearance between the board and the base plate, so I ended up asking Xduoo directly. It was very nice of Xduoo to respond with such detail (see Xduoo responses here), it really answers all my TA-20/opamp questions

Which Mullards did you get? Link? I have posted some recent ones I've bought that I enjoy in this post:
https://www.head-fi.org/threads/xduoo-amplifiers.682282/post-16699553

 

[PetFju]

Moving discussion from here:
https://www.head-fi.org/threads/the-opamp-thread.432749/post-16699436

Yeah, not much out there on swapping TA-20 opamps, likely due to the small clearance between the board and the base plate, so I ended up asking Xduoo directly. It was very nice of Xduoo to respond with such detail (see Xduoo responses here), it really answers all my TA-20/opamp questions

Which Mullards did you get? Link? I have posted some recent ones I've bought that I enjoy in this post:
https://www.head-fi.org/threads/xduoo-amplifiers.682282/post-16699553

Got a matched pair (not that it matters tho ) of Mullard 12AT7WA / CV4024 Do not know more about them really, but they are modern variants i believe
Edit; i checked now, they're actually NOS tubes.

 

[PetFju]

I am also considering getting a pair of Genalex Reissue 12AT7 ECC81 GOLD PINS https://www.ebay.com/itm/1528916184...&brand=Genalex&_trksid=p2506613.c100290.m3507

 

[hmscott]

I am also considering getting a pair of Genalex Reissue 12AT7 ECC81 GOLD PINS https://www.ebay.com/itm/152891618472?_trkparms=amclksrc=ITM&aid=111001&algo=REC.SEED&ao=1&asc=20160727114228&meid=791b179fe3bd478d884c3403c549eb33&pid=100290&rk=1&rkt=4&sd=152891618472&itm=152891618472&pmt=1&noa=1&pg=2506613&brand=Genalex&_trksid=p2506613.c100290.m3507

I have a pair of the Genalex Reissue 12AU7's and they sound good, and I was wondering how the Genalex Reissue 12AT7's might sound, please report back after you've run them for a while - usually 100-200 hours is enough, and let us know how they compare to other tubes you enjoy

I do recommend Viva Tubes, I've bought from them before myself, but I usually shop for the lowest price, and right now that is also tubemazestore on ebay:
https://www.ebay.com/sch/i.html?_nk...pins&_sacat=0&LH_TitleDesc=0&LH_BIN=1&_sop=15

Matched Pair Genalex ECC81/12AT7/B739 tubes Gold Pins - Russia
https://www.ebay.com/itm/174820418205

Even without the 20% Holiday Discount, their price is lower than Viva Tubes... either one would be fine, maybe Viva Tubes would do price matching if you asked nicely?

 

[PetFju]

I have a pair of the 12AU7's and they sound good, was wondering how the 12AT7's might sound, please report back after you've run them for a while - usually 100-200 hours is enough, and let us know how they compare to other tubes you enjoy

I do recommend Viva Tubes, I've bought from them before myself, but I usually shop for the lowest price, and right now that is also tubemazestore on ebay:
https://www.ebay.com/sch/i.html?_nk...pins&_sacat=0&LH_TitleDesc=0&LH_BIN=1&_sop=15

Matched Pair Genalex ECC81/12AT7/B739 tubes Gold Pins - Russia
https://www.ebay.com/itm/174820418205

Even without the 20% Holiday Discount, their price is lower than Viva Tubes... either one would be fine, maybe Viva Tubes would do price matching if you asked nicely?

Thank you for the tip about the different shops. I usually try to buy locally, as there is at least a semi-probability of getting any issues that might arise resolved quickly and without too much hassle.
I will let you know how i find the new tubes, read somewhere else (can't remember where) that the 12AT7's are a good pairing for this amp. But i guess we'll see. But i do have some hopes for better sound, because right now the Little Dot 1+ (although modded quite a bit) actually sound better with a wider soundstage and in general better tonality than the TA-20. And i have no doubts about the fact that the TA-20 is the superior amp, it just needs a little bit of love

 

[hmscott]

Thank you for the tip about the different shops. I usually try to buy locally, as there is at least a semi-probability of getting any issues that might arise resolved quickly and without too much hassle.
I will let you know how i find the new tubes, read somewhere else (can't remember where) that the 12AT7's are a good pairing for this amp. But i guess we'll see. But i do have some hopes for better sound, because right now the Little Dot 1+ (although modded quite a bit) actually sound better with a wider soundstage and in general better tonality than the TA-20. And i have no doubts about the fact that the TA-20 is the superior amp, it just needs a little bit of love

Well, tube only amps will give more "tubey" sound, but I've found the 12AT7 Mullard's of the links I've shared, in my TA-20, have given the widest sound stage and most focused sound for directionality - instrument and "enemy" placement, while being not too expensive.

I've ordered these Mullard E180CC tubes, and will report back when I hear them, I'm hoping they are the 12AT7 version of the E80CC tubes:

Matched Pair E180CC NOS Mullard Holland Valve Tubes
https://www.ebay.com/itm/111861807456

They also have unmatched single tubes for less:

E180CC 5965 12AV7 NOS Mullard Holland Valve Tubes
https://www.ebay.com/itm/112112339682

I've also seen Mullard E80CC tubes, maybe next month

 

[Silver Wolf]

Have to just look often and keep your eyes peeled for NOS deals.

Just scored a matched pair NOS Mullard m8162 tubes (build: 1968 models, Mullards own factory at Mitcham), even the boxes still look minty... $60 isn't bad, I'm happy.

Been stuck on these old 12au7 Brimars, will be my first set of 12AT7 in the TA-20

 

[PetFju]

So my Mullard tubes got stuck in shipping. So still no news on those 12AT7 mullards as of yet. But i did get a pair of NOS 12AU7 WE JAN GE tubes. I have the samy brand/type in my Little Dot 1+, where they excel, and figured i could try the 12AU7 versions as well, just for the hell of it. I know it's not apples to apples comparison, but i figured it was worth a shot.
So far i have played 4-6 hours on them and they certainly sound cleaner than the stock tubes. However, they are almost TOO clean. I'll have to give them another 10-20 hours before i judge them, but as of now they are just very very "accurate" sounding, and has a medium/normal soundstage with a good amount of separation.
I am looking forward to having them go head to head with the Mullard tubes
Btw; so far they have made it so that the TA-20 by far has outdone the Little Dot as far as sound quality goes, so they are certainly doing something right..That is on the Hifiman Sundaras as well as the Sennheiser 58X jubilee's.

 

[PetFju]

On another note; i just got a "collect-notice" on two pairs of matched RCA cleartop 12AU7 from tubedepot. I forgot i ordered those..lol But i'll have a go with them throughout the week-end as well, and i'll post my findings. Have a good one out there!

 

[PetFju]

Ok, so after a few hours on the GE 12AU7WE JAN and the RCA 12AU7 cleartops i am surprised to say the differences aren't glaringly obvious.
So far i do not get all the hype around the RCA tubes, but it might just be that they need more burn-in.
I did however recieve my "Royal Air Force" Mullard CV4024/12AT7's. And oh boy...They've only been in the TA-20 for less than 30 minutes, and as such one can say that they're not burned in, or even warmed up for that matter, but the sound..This is why i got a tube amp in the first place. Just airy and big, with taut bass, yet detailed and smooth highs. If this carries on, or gets even better with time, i honestly think these tubes are a golden pick for these amps.
I will update after some time has passed. Have a good week-end everyone!

 

[CJG888]

Where did you get RAF surplus CV4024s?

 

[PetFju]

Where did you get RAF surplus CV4024s?

I sourced them locally here in Norway. Also i didn't know they were RAF surplus until i checked their markings/designation.
I see now that the ad is down, so i don't know if he has any more of them, but you could contact him at:

https://www.hifisentralen.no/forumet/members/kimandersen.25342/

Please note that this forum is norwegian, and as such you might have some language issues..

-Pete

Edit- Btw, i see these are also sold here: https://upscaleaudio.com/products/mullard-cv4024-12at7

 

[PetFju]

"Deleted" - Can be removed by admin